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Ch. 5 Lecture Notes
Atomic Structure and the Periodic Table
5-1 Atoms
A. Early Models of the Atom
1. ____________________ – 4th century BC – world made up of empty space and
tiny particles called _______________ (atomos) ‘indivisible’
a. Hypothesized _________________ using experiments
B. __________________ Atomic Theory
1. All matter is made of ________________
2. Atoms are _______________________ and cannot be __________________ into
smaller particles (later proved _______________)
3. All atoms of one element are exactly _____________ (later proved wrong),
but they are _____________________ from atoms of ___________ elements
4. Atoms combine in simple whole number ______________ to form
_____________________
5. In chemical reactions, atoms combine, separate, or are rearranged.
5-2 Structure of the Nuclear Atom
A. Atomic Structure
1. _______________: (e-)
a. Discovered by ________________ cathode-ray tube (1897)
• _________________ Ray = positive and negative electrodes
connected, beam travels from cathode (-) to anode (+)
b. Found electrons have ______________ charge
 Beam in cathode ray attracted to anode (+), must be negatively
charged.
 Relatively no ___________ (experiment by _________________ 1916)
2. _______________ – has positive charge (p+), greater __________ than an electron
a. Discovered by _________________ in 1886
3. _______________ – has ______________ charge (no), _____________ in mass to proton
a. Discovered by _________________ in 1932
4. ________________ = small, ________________ charged central core, made up of
__________________ and neutrons
a. Discovered by _____________________ gold foil experiment in 1911
b. Fired stream of positive particles at gold foil, most passed right
through (atom mostly _____________ space) while a few bounced off
(very _______________ positive nucleus at center)
B. Development of Modern Atomic Theory
1. ___________ of conservation of matter (mass) = in a chemical reaction matter
is neither created nor destroyed.
a. All elements are recycled/________________!!
b. Law of definite ____________________ = elements within a compound
are always in certain proportions by __________
 Ex: NaCl (table salt) is always 39% ______ and 61% ______.
5-3 Distinguishing between Atoms
A. Atomic Number
1. __________________ = number of _________________ in the nucleus of an atom
atomic # = _________
a. Determines the ______________ of the element
b. Periodic table is organized by atomic _____________
c. Ex: What is the atomic number of He ______, C _____, N ______, O ______
2. Also # of protons = # of ___________________
p+ = ________
a. Ex: How many electrons does Cl have? _______
B. Mass Number
1. ______________ = _____________ of the protons and neutrons
mass # = ________________ Why do we not include electrons??? ______________
neutron = mass # - _________________
2. Periodic Table symbols:
12
_____________________
C _____________________
6
_____________________
C. Let’s Practice!
1. How many?
Write it:
Protons
____
____
Neutrons
____
C
Electrons
____
____
2. How many?
Write it:
Protons
______
____
Neutrons
______
S
Electrons
______
____
D. Remember!!!
1. Mass # = ______________
2. Atomic # = __________
3. e = ________
4. n = _______________________
E. Atomic Mass + Isotopes
1. Atomic __________ = weighted average mass of ________________
2. __________________ = one element with __________ proton # but _________________
neutron #
a. Carbon has 3 possible isotopes:
14
13
12
6 C Carbon-________, 6 C Carbon-_______, 6 C Carbon-____
F. Try it!
37
1. Ex: Isotope of Chlorine: 17
Cl p+ ______, no ______, e- ______
G. Atomic Mass Unit
1. Atomic Mass Unit (________) = 1/12 the mass of a carbon-12 atom.
a. Used to ___________________ element’s masses to a standard.
b. ___________ for measuring atom’s masses
5-4 The Periodic Table: Organizing the Elements
A. Development of the Periodic Table
1. In 1869, ___________________ created Periodic Table of Elements
a. Organized it by increasing atomic _________ and elements with
similar ____________________ in same columns.
b. Able to _______________ future elements properties
2. In 1913, _________________ organized it by atomic ______________.
B. Modern Periodic Table
1. Organized by atomic ________________
2. Periodic _________: grouped according to physical and chemical ______________
3. _____________ = horizontal _________ of periodic table; numbered down the
side, ______ periods
4. _____________ = vertical _________________, also called a family; _____ groups
C. Group Designations
1. ______________________ elements = Group 1, 2, ____________
a. Group 1 – ________________ metals
b. Group 2 – Alkaline ______________ metals
c. Group 17 – __________________
d. Group 18 – ______________ gases
2. Transition _____________ = groups 3-12
D. Physical States of Elements
1. Periodic Table shows the states of the elements at ______________
temperature and normal ____________________________.
a. Most are _______________________
b. Only two are ________________________
c. ____________________ elements are in the top right hand corner except
for Hydrogen
d. The rest are made ______________________ (man-made) through
________________ reactions (43, 61, 85, 87 and >93)
E. Classifying Elements
1. ______________ - majority of elements, occupy ____________ side and center,
_________________ of the staircase.
2. ______________ - occupy top ____________ hand corner (includes ______), _________
of the staircase.
3. _______________ - along the ________________
F. Metals
1. Have ______________, many _______________, conduct ___________ and electricity,
usually bend w/o breaking (___________________)
2. Almost all are _______________ at room temp and have extremely high
___________________ points
G. Nonmetals
1. Are abundant in ________________
a. Oxygen and Nitrogen: 99% _____________________
b. ___________________ in more compounds than all others combined!
2. _____________ conductor of heat and electricity, _______________ when solid
3. Many _____________ at room temp, __________ melting point
H. Metalloids
1. Have properties of ___________ metals and nonmetals
2. ______ Metalloids: B, Si, _____, As, Sb, ____, Po (touches staircase except _____,
_______)
3. Some are _______________________ = element that does not conduct electricity
as well as _____________, but does conduct slightly better than _________________
a. Ex: _______________ – used in computer industry